Lifespan among other mammals is usually short because the required training to make it is not that complicated, unlike in a complex human or even great ape society. By the way the life expectancy of most cavemen was less than 40 years, and compared to horses and elephants, it's not that long. Only in recent times through agricultural and technological advances and good life has life expectancy increased. So this ultra life expectancy of 80 years may not be long because the brain requires it or demands it, but more like the brain allows it, so why not? Having great-grandmothers, grandmothers mothers and daughters together in a village, usually makes for a more successful village where members proliferate marrying into other villages taking their customs of sticking together through the long generations, and having long generations, compared to short lifespan mother-child only structures usually found in the wild, where the grandmother and great grandmother don't participate, and don't make a difference whether they still exist or not.

If half the people born die in infancy and the other half live to 80, the *average* life expectancy will be 40 years. Is that what you were referring to? (And no, I'm not saying that the extreme polarised example I gave *was* the case, just that high infant mortality may skew the average age in a manner that makes it meaningless for predicting the lifespan of those who reached adulthood).

I bet diapers are standard gear in space. You cannot shit properly without gravity.

Thank God you both have imagination and speculation to help fill in your gaps in knowledge.

If only someone could invent a vast, searchable information databank that was computer accessible via network where you could answer these inquiries then perhaps you might not be forced to speculate as much. I would call such a thing a CompuNet.

I was thinking of a light suction vacuum cleaner device with a centrifuge separator, that has soft foam to conform to the shape near your anus. The light suction would come about from a Y or F connection, where some of the air is taken from the room at very high speed, and that opening has an adjustable flap, and you still get enough speed and velocity to centrifuge separate the liquids and solids, regular wet-vac style. Maybe something insertable, but now we're stepping into gay territory that some people

Try every few days. I remember the annoyance of making sure I cleaned out the pipes before sleeping over at anyone's house. During my peak, it wasn't uncommon to take care of business a few hours before bed and still having the issue.

There was an interview with some astronauts that mentioned they just had some more professional sounding phrase of something like 'private time'. Not to mention the prostate cancer risk between daily and monthly release is about 3x worse for monthly. This has been found in se

That there is an inverse correlation between brain glucose use and body growth does not imply that the brain's use of glucose stymies the growth until later.If that were the case, kids who are overfed carbohydrates would be smarter and taller, not fatter and dumber.

My guess is that slow growth is selected for because children who look like children enjoy special care and protection by adults. Growing to adult size by age 7 might be detrimental to survival.

What utter fucking rubbish. Getting to the point you can run / fight according to Darwin and thence eventually able to breed is more beneficial. Being a walking target for disease and predators is from a Darwin perspective really bad, growing up fast is what should have been selected.

Yup, and what makes it even more rubbish is the idea that simply feeding someone more food is enough to change their biochemistry, metabolism, and energy distribution budget towards diverting more energy towards growth and less towards the brain, and that blood glucose levels are determined by dietary carbohydrates.

But I do enjoy reading the pseudo-intellectual armchair philosophizing that we see so often.

Nobody should be allowed to comment on genetics or evolution until they've read The Selfish Gene. While some small parts of it are arguably out-dated, it really helps orient one's mindset regarding evolutionary genetics. The Selfish Gene will survive as an extant and useful work much longer than Darwin's On the Origin of Species.

Even many biologists should read it. Too many biologists lack rigor when they hypothesize about evolutionary behavior. The Selfish Gene really lays out not only what has been effectively proven about evolutionary genetics, but provides examples of the complex but elegant mechanisms that _new_ evolutionary processes (e.g. group selection) will probably also look like if they can ever be proven.

No-one should be allowed to comment on anything if they have read The Selfish Gene. Dawkins is a dangerous hack and a terrible writer. His pop-science books never educate the state-of-the-art, but instead indocrtrinate his view to the exclusion of all others.

Not necessarily. The major threat to children in primitive hunter gatherer societies is not predators but hunger. By staying smaller during their formative years, they reduce the amount of calories need to survive. But the selection pressures are different on boys and girls. Girls are generally able to procreate as soon as they reach puberty. But boys need to wait till they are older, and have built up social status. So it makes sense for girls to mature faster, and that is what happens. Look at a group of kids in 4th or 5th grade, and the girls are several inches taller than the boys.

Not necessarily. The major threat to children in primitive hunter gatherer societies is not predators but hunger. By staying smaller during their formative years, they reduce the amount of calories need to survive.

This. Also, it takes time to learn the vast amount of information that it takes for a human being to really be smart enough to manipulate its environment... which evolution has obviously selected for. Chimps, for example, often actually outpace human learning for up to 2 years, but then humans continue to learn while the chimp rapidly levels off. Keeping resource use to a low level during this long learning phase is likely a long-term survival trait.

Also it should be noted that another factor in humans' slow growth is already known: humans can only have babies with brains so big, before birth becomes a very big problem. So a longer period is needed for the human brain to grow to its adult size.

But the selection pressures are different on boys and girls. Girls are generally able to procreate as soon as they reach puberty. But boys need to wait till they are older, and have built up social status. So it makes sense for girls to mature faster, and that is what happens. Look at a group of kids in 4th or 5th grade, and the girls are several inches taller than the boys.

It is more accurate to say that boys and girls mature at different rates.

If you adjust for the probable influence of estrogen mimics in our current environment, human females start to mature sexually before males do, but actually finish their sexual maturation later. You are referring more to social factors than genetic: often males need to be older to establish themselves in order to semi-permanently mate, but that is not the same things as physical sexual maturity needed to procreate.

These are not separate factors. Genes influence social behavior, and social behavior influences which genes are selected. In ALL human societies, men prefer women younger than themselves that are physically attractive, which correlates with fertility. In ALL human societies, women prefer men with high social status, and greater resources. It is unlikely that such universally pervasive preferences are purely "social" rather than genetically innate. Chimpanzee males have no preference for younger females, and when given a choice of mates, will prefer older females. Female chimps do not have the same decline in fertility with age that women have, and more mature and experienced females have a greater chance of successfully rearing offspring.

In ALL human societies, men prefer women younger than themselves that are physically attractive, which correlates with fertility. In ALL human societies, women prefer men with high social status, and greater resources.

As a generalization, this is true enough. So, I will amend my comment. They might be genetic factors, but they aren't overt physical factors. The fact that males tend to be older when they mate is not a matter of sexual maturity, which generally comes long before then.

It takes a long time to teach our kids because the system we have for teaching them is horribly inefficient and has been for thousands of years at this point.

But it carries on not because it's good but instead because it is so indoctrinated and there is no allowance to try anything radically different. If you try even things like "new math" parents freak out because that's not what they learned.

In fact, the entire schooling process we have, from primary schools to colleges and post-graduate should be reexa

It takes a long time to teach our kids because the system we have for teaching them is horribly inefficient and has been for thousands of years at this point.

Until around 1900, within the working class (which generally included lower middle class back then), education was reading, basic writing and arithmetic. A 12 year old - whether boy or girl - was expected to be a productive member of working class society and was often married (12 for girls and 14 or so for boys). Education beyond that was for the upper class (and upper middle class), especially university level education. Extending education through grade 12 (typically age 17 or 18) for (nominally) all you

It's interesting how for most of human history people were partnering up and and having babies around 14/15 yrs old and being grandparents at 30 yrs old and great grandparents at 45 yrs for the few that were lucky enough to live that long.

Now in our highly specialized society, people are commonly having babies in the mid-30s.

My son is 5. In dog years he would be running/fighting/making Darwin happy by now. In reality he is very clumsy and unprepared to run/fight. If he were adult-sized by now it would be a major disaster, which would make Darwin very unhappy. On the plus side his intelligence surpassed the smartest of dogs by now, making Darwin very happy. Cut the BS and learn to apply Darwin correctly.

Try behaving like a seven-year-old in grown man's body (on the webs doesn't count), see how that works for you. Your older peers will be a bigger threat to you (and you to them) than disesase and predators.

You can scream this at the top of your lungs until you are blue in the face, but it probably won't make a difference. Explaining it carefully might convince a few people, but not about things they already believe in. Its been said so much that you wouldn't even post it under your username, because you know it will get adversely moderated. People have read it so much they cringe when they see it.

You'll never be able to convince people that toasters don't cause suicidal tendencies in teenagers.

You'll never be able to convince people that toasters don't cause suicidal tendencies in teenagers.

Depends on the toaster, wouldn't you agree? I have had toasters that made me want to kill whoever sold it to me.

I think, if we take away the hype and the misunderstandins on the part of the article, that what we have here is an interesting observation that does support the theory that brain-growth may be one of the factors determining when we become adults. I don't think it is true, though; it seems to me that the biggest evolutionary advantage we have is, in fact, the prolonged period of brain development and plasticity and the evolution of the family unit that supports a long childhood; this, incidentally, includes the fact that we, as the only species I know of, also live long after reproduction. Having grand-parents who can pass their experience on to the youngest, seems like a huge advantage to me.

'Imply' means something different in formal logic. You can use this line instead: "Just because two things happen at almost the same time doesn't prove that the first one caused the second."

The guy who got shot in the brain could have had a heart attack seconds earlier. You still need to do the autopsy to prove that the shot was the cause of death. Yeah, it probably was, but 'probably' isn't proof.

No, it doesn't. You have the wrong idea of what "imply" means. It is not a synonym for "hint at" or "suggest" any more than "implication" is a synonym for "hint" or "suggestion". It is a near synonym to "mean".

That you have two X chromosomes and no Y chromosome implies that you are female. It does not merely hint at it.

When I used the word imply in the real world example of my GPP, it was to say exactly what I said. Not your uneducated guess at what it means.

we're talking about the real world, so the formal-logic definition of imply doesn't apply. It only makes sense in math. Imply in real-world terms means hint at.

Just because the real world is full of illiterate people, that does not mean the precise meaning of words suddenly vanish. The mindless masses murder the language all the time using the wrong words to express what they want to say (if they even had the capacity to build a cogent statement).

"Imply" is "imply" and it is distinct from "hint" - check your dictionary. Yes, real world people are too stupid to use a dictionary, but that doesn't invalidate the definitions in it.

You can use this line instead: "Just because two things happen at almost the same time doesn't prove that the first one caused the second."

You are using "imply" in a more casual sense, which would be fine if you didn't also call him wrong. Now that you've broken out the weird pedantry, I have to tell you he's not wrong, he's actually perfectly accurate and you're being pedantic.

Really? That hypothesis doesn't make a lot of sense to me. Larger and stronger at a younger age would seem to be a good survival trait, not a bad one. It doesn't seem like the benefits of parental protection instincts for young children would outweigh the negatives of being weaker and smaller, purely on the basis of survival traits. Besides which, I don't think parental protection instincts necessarily disappear when a child reaches adulthood. Talk to my mother if you're not convinced.

The evolutionary reality is even simpler that that (though the achievement of those is clearly not). The three main factors are:

1. be able to reproduce2. be able to attract/acquire a mate3. be able to care for/protect offspring long enough for them to reach #1

Clearly if it was just up #1 we would still be living alongside the rest of the primates. #2 can be a fairly complex social interaction - but insects are just as capable of it as humans. #3 is where the whole thing explodes, and is the key to investing all of those resources into the brain (and is what made it more evolutionarily advantageous to extend the time to #1 and #2).

Though of course in modern human society, social and technological advancement in #3 has so outpaced the first two that they barely seem to matter, and is why we are basically blowing past any "natural" population control. Our brains are letting us find clever ways of surviving and stripping the planet of resources, but unless we figure out a way to expand beyond the planet or stop using its finite resources we'll go through the same collapse seen in any other species going through a population explosion...

Weirdly, your incoherent/drunken/moronic post almost seems to be proof that humans "evolved better mothers from taking care of the infants". Can't think of another explanation. Are you *still* in your mother's basement or is she just paying your rent?

Larger and stronger at a younger age would seem to be a good survival trait, not a bad one. It doesn't seem like the benefits of parental protection instincts for young children would outweigh the negatives of being weaker and smaller, purely on the basis of survival traits.

It is axiomatic that, as far as Homo sapiens is concerned, evolution disagrees with you. I believe the reason is you limit what survival traits are to less than what they truly are.

Humans are by far the most intelligent creatures on this world, and thanks to that intelligence can learn a lot.

Learning primarily takes place in the childhood stage, when parents directly teach their children all they need to know to survive (which until not so long ago, was indeed mostly survival skills: how to grow your own food and so). A long childhood (and with that, long parental care) may for this reason be an advantage: longer time to learn typically makes for a better end result.

This doesn't really follow. Animals that suddenly find themselves an abudance of food don't grow massive, rather they reproduce in greater numbers. If food were always highly available then we might select for large size and big brains over time, but any one person with too much food is not going to suddenly become superman.

I'm not an expert in this, but my guess is that our energy hungry brains are one of the factors in the relatively long development period for our offspring, but it's not the only fa

Well, glucose in the blood is basically a toxin; by overfeeding carbohydrates you're really just taxing the bodies ability to cope with blood sugar (IE, insulin spikes and making you fatter).

The brain has its own needs, and will take what it needs basically no matter what. Not enough dietary carbohydrates to provide glucose? No problem, some of your muscle (or protein from our diet) is broken down and converted by the liver. Bear in mind the amount of glucose the brain needs per hour, and the fact that

You assume the body can process as much glucose as you can feed it, which simply isn't true. There's a point where any glucose beyond this threshold is "wasted" for the purpose of positive development, but it does still get processed (into fat). Put another way, the a child's body is a machine that can process 100 units of glucose (arbitrary number) at any given time, 80 of which go to the brain. If you feed it 120 units of glucose during that time, it still only processes 100. Again, 80 goes to the bra

"If that were the case, kids who are overfed carbohydrates would be smarter and taller, not fatter and dumber."Every look at an AP class? Fatter does not mean dumber.Of course the best combination might be a high carbohydrate and a high activity diet for young people.

If that were the case, kids who are overfed carbohydrates would be smarter and taller, not fatter and dumber.

Now who's drawing premature conclusions!

Here's the legendary Slashdot car analogy. Put an 850 CFM Holley on a straight six in a 1960s Pontiac Lemans. Will that turn it into a GTO? No! The human body can't process those calories any faster. They have to be changed into glucose.

Your implication that being overweight makes kids dumber is so stupid, I wonder what your motivation is.

The human body can't process those calories any faster. They have to be changed into glucose.

They already have been changed to glucose before they become fat, which means that the body quite obviously could process them. That they became fat is because there weren't any takers for the glucose.

1. The correlation between obesity and intelligence doesn't seem to have a connection. There is a stronger correlation between obesity and poverty and poverty with low test scores. But that is chaining a bunch of consolations together to come up with a faulty premise. You will need to compare Intelligence of Fat vs Skinny people in similar economic environments.

2. Obesity is a factor of over use of a nutrients, not a normal healthy usage.

Wow, I can't believe that someone missed the point so completely!The point being that it is unlikely that the brain is stealing the glucose and thus stunting growth like the article supports, because when kids are fat, that means they have metabolized carbs->glucose->fat, and thus have had plenty of glucose. That fat kids' bones don't appear to shoot past normal kids in growth strongly suggest that there are other reasons why kids don't grow physically to adults in half the time.

Glucose is a strict subset of 'carbohydrates'... many of which are more fructose (which tastes sweeter without triggering 'no longer hungry' warnings) or sucrose (which is some sort of glucose/fructose combination) than pure glucose (which basically everything in the body uses as fuel).

Fructose/Sucrose at least seems to lead to "fatter and dumber"; not sure there are any records of what happens when you go with a primarily glucose-based diet.

Humans also have a lot more to learn than other primates: e.g. language and culture. It makes sense that we evolved with extended childhoods to give us time to learn things.

Neoteny: [wikipedia.org] It's well-known that humans have an innate attraction for the general proportions of children: small, with big eyes and a large head. The longer kids look like kids, the more likely parents and other humans are likely to nuture, protect, and teach them.

I would speculate that it's simply that, for humans in their eusocial foraging societies, brain development was the priority and there was no point in reaching sexual maturity and adulthood before the brain had developed and the individual had learned enough to be a full member of the community. The brain and the rest of the body are not competing for glucose, the brain is simply the critical path and the rest of the body has no need to develop faster.

I decided to fact check this claim. Eusociality, according to Wikipedia and the references it cites, is defined as three aspects of the behavior of a species:

"cooperative brood care (including brood care of offspring from other individuals)": Daycare is a thing.

"overlapping generations within a colony of adults": Grandparents are a thing.

"a division of labor into reproductive and non-reproductive groups": Humankind appears to be moving in the direction of breeder vs. thinker classes. More affluent classes already tend to produce fewer children, and the public has become more accepting of a gay lifestyle. Furthermore, I've seen plenty of contempt for "breeders" and other childfree-by-choice advocacy on Slashdot.

I agree that humans are not as close to the eusocial ideal as bees and mole rats, but we're closer than a lot of other species.

Being gay doesn't automatically exclude someone being a "breeder". It does introduce challenges, both biological and social. I have plenty of gay friends who are parents or are trying to become parents.

That said, at least in the US, the job market encourages workers to not be parents. Partly from this, and partly from other reasons, there are plenty of non-gay relationships that choose to not have children and have even obtained medical treatment to prevent accidental pregnancy. (Side note: The logic of the

For most species, childhood is all risk, no benefit (where benefit = breeding), and so it is to be got through as fast as possible (or at least in time for next breeding season). If glucose shortage was the only reason for doubling the length of our childhood, there would be a huge evolutionary pressure towards kids who could metabolize much more food and reach adulthood in half the time.

There is an obvious reason why humans have such a long childhood - it is because we have so very much to learn. Little bodies can learn as well as big bodies, and cost less to maintain.

If it is the brain stealing calories that slows development, how come when you feed a child a high-calorie diet he becomes a fat child rather than a young adult?

How about this: if we took only three years (or less!) to reach adulthood like some animals, you'd have toddler with an adult body. I'm pretty sure it's actually an advantage that our young are easily restrained. It's actually rather common for more intelligent creatures to take longer to mature. Taking longer to prune the excess synaptic connections seems to allow for greater learning at the cost of slower development. In the case of humans, we're also born with an especially undeveloped brain and a squishy skull, for which your mother is probably grateful.

WE have some wierd fetish with letting kids be kids for as long as possible. Sorry but at 13 you are biologically an adult so you need to have adult responsibilities and adult expectations. these teenagers need to get off their asses and work, build, etc.. Instead we extend this out to age 20 before we expect them to get a job and start being responsible.

Less than 100 years ago it was not uncommon for marriage at age 16 and that young couple working hard to build their family Average age of a woman getting married was around 21 years of age. Today it is far higher at 26 years of age and insanely uncommon for a 16 year old marriage, Although outside the USA it is far lower. Mexico has a median for women at around 18 years old. Many states in the USA still have the age of consent at age 16. This means that 16 year olds can make decisions as an adult, yet for some reason we think they cant today and are still children.

Note on marriage ages, some of this is economics, back 100 years ago it was a lot easier to make a living as you made about $35.00 a month working at a foundry or smelter and typically renting a house is $5.00 a month less that 20% of your income was your rent. today most of the young pay 60% of their income as rent and have to split that rent with room mates because they can not even hope to even meet rent with their meager income. So 100 years ago it was easier for young and uneducated to make it in the world with the sweat of their brow.

So many poor assumptions there. The average life expectancy was a lot less 100 years ago: http://demog.berkeley.edu/~and... [berkeley.edu] Consequently, people got married earlier because they died sooner; this goes back through the beginning of recorded history, and it was really only in post-WWI 20th century that marrying while a teenager became not just not the norm, but socially frowned upon. Also, look at the drops in life expectancy in 1918 and 1943; what you are seeing it the effects of both world wars and the sp

WE have some wierd fetish with letting kids be kids for as long as possible. Sorry but at 13 you are biologically an adult so you need to have adult responsibilities and adult expectations. these teenagers need to get off their asses and work, build, etc.. Instead we extend this out to age 20 before we expect them to get a job and start being responsible.

More like not allow them to get jobs or otherwise have the legal authority to function as adults. There are very few, if any, jobs anyone under 16 is legally allowed (not counting allowance for doing family chores). And not many that 16 and 17 year olds are legally allowed. At age 10, my daughter wanted a real, paying job. And she was actually capable of doing meaningful office work. She also wanted to stay in school. She thought she could handle 2 hours per day of office work along with her studies. She mi

This article is incorrect, as everyone else said. Eating more sugar doesn't make you grow faster so it's wrong. If children grew any faster, their bones and joints wouldn't take the stress. My evidence is kids who grow too fast and have bone and joint problems (duh). Also, if they grew any faster, they were be even less coordinated due to limb length alterations and prone to accidental injury or death.

"Humans are late bloomers when compared with other primates -- they spend almost twice as long in childhood and adolescence as chimps, gibbons, or macaques do."

And since chimps, gibbons, and macaques are the dominant life forces on the planet -- what with their iPhones and running water and skyscrapers and space programs and whatnot -- it is obvious that this difference in growth is a PROBLEM that must be FIXED.